Flush toilet

ABSTRACT

A toilet bowl portion, a rim portion that forms a peripheral portion of an upper end opening of the toilet bowl portion, a first rim water discharge port formed on an inner circumferential wall portion of the rim portion, and a first rim water passage that is formed on the outer circumferential side of the toilet bowl portion and is for supplying washing water to the first rim water discharge port are provided, and the first rim water passage has a turned-back portion that guides washing water to turn back from one side to the other side in the circumferential direction of the toilet bowl portion, a portion of an outbound portion and a portion of an inbound portion that continue to the turned-back portion being arranged while being lined up in the vertical direction.

REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 USC 371 of International Application No. PCT/JP2016/070688, filed Jul. 13, 2016, which claims the priority of Japanese Application No. 2015-188302, filed Sep. 25, 2015, the entire contents of each of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to flush toilets.

BACKGROUND OF THE INVENTION

A flush toilet is usually provided with a toilet bowl portion, a rim portion that forms a peripheral portion of an upper end opening of the toilet bowl portion, a rim water discharge port that is formed at an inner circumferential wall portion of the rim portion, and a rim water passage that is formed on the outer circumferential side of the toilet bowl portion and is for supplying washing water to the rim water discharge port.

As this type of flush toilet, a flush toilet has been suggested that is provided, at a rim water passage thereof, with a turned-back portion that guides washing water to turn back from one side to the other side in the circumferential direction of a toilet bowl portion. In this flush toilet, it is considered that, by discharging washing water to a section to which waste is likely to be scattered, it is no longer necessary to increase the force of washing water, and splashing of water to the outside of the toilet bowl portion can thus be prevented.

Patent Document No. 1 Japanese Patent Application Publication No. 2011-208362

SUMMARY OF THE INVENTION

In a flush toilet according to Patent Document No. 1, both an upstream side portion and a downstream side portion with respect to a turned-back portion of a rim water passage are arranged while being lined up in the lateral direction. According to research conducted by the inventors of the present invention, it is found that there is room for improvement in a conventional structure from the aspect of increasing the discharge amount of washing water from a rim water discharge port while reducing the outer width dimension of a rim portion.

The present invention has been made in view of such a problem, and a purpose thereof is to provide, in the case of providing a turned-back portion in a rim water passage, a flush toilet that has a structure suitable for increasing the discharge amount of washing water from a rim water discharge port while reducing the outer width dimension of a rim portion.

To solve the problem above, one embodiment of the present invention relates to a flush toilet. The flush toilet comprises: a toilet bowl portion; a rim portion that forms a peripheral portion of an upper end opening of the toilet bowl portion; a first rim water discharge port that is formed on an inner circumferential wall portion of the rim portion; and a first rim water passage that is formed on the outer circumferential side of the toilet bowl portion and is for supplying washing water to the first rim water discharge port, wherein the first rim water passage has a turned-back portion that guides washing water to turn back from one side to the other side in the circumferential direction of the toilet bowl portion, a portion of an outbound portion and a portion of an inbound portion that continue to the turned-back portion being arranged while being lined up in the vertical direction.

In order to have a structure suitable for increasing the discharge amount of washing water from the first rim water discharge port while reducing the outer width dimension of the rim portion, a passage cross-sectional area at a section where the outbound portion and the inbound portion are lined up is made to be large. According to the present embodiment, the passage cross-sectional area at the section where the outbound portion and the inbound portion are lined up can be made effectively large in the vertical direction while preventing an increase in the dimension of a partition wall portion that separates the outbound portion from the inbound portion compared to a case where the outbound portion and the inbound portion are arranged while being lined up in the lateral direction. Therefore, a structure can be provided that is suitable for increasing the discharge amount or washing water from the first rim water discharge port while reducing the outer width dimension of the rim portion.

According to the present invention, in the case of providing a turned-back portion in a first rim water passage, a structure can be provided that is suitable for increasing the discharge amount of washing water from the first rim water discharge port while reducing the outer width dimension of a rim portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the flush toilet according to a first embodiment;

FIG. 2 is a cross-sectional view taken along a line A-A of FIG. 1;

FIG. 3 is a cross-sectional view taken along a line B-B of FIG. 2;

FIG. 4 is a cross-sectional view taken along a line C-C of FIG. 3;

FIG. 5 is a cross-sectional view showing, in an enlarged view, a left rim water passage according to the first embodiment;

FIG. 6 is a schematic diagram of a cross section cut along a line D-D of FIG. 5, the cross section being expanded in a plane;

FIG. 7 is a cross-sectional view of a flush toilet according to a reference example, the flush toilet being viewed from the same viewpoint as that of FIG. 4;

FIG. 8 is a lateral cross-sectional view showing a flush toilet according to a second embodiment; and

FIG. 9 is a schematic diagram of the flush toilet according to the second embodiment, the flush toilet being viewed from the same viewpoint as that of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

In the following embodiments and exemplary variations, same numerals represent same constituting elements, and duplicative explanations will be omitted. For the sake of ease of explanation, some constituting elements are appropriately omitted in the figures.

FIG. 1 is a plan view of a flush toilet 10 according to the present embodiment, and FIG. 2 is a cross-sectional view taken along a line A-A of FIG. 1. The flush toilet 10 is provided with a toilet main body 12 made of ceramics. The toilet main body 12 is a floor mounted type toilet that is installed on a floor 100 of a toilet room.

As shown in FIG. 2, the toilet main body 12 is provided with a toilet bowl portion 14 and a water drain passage portion 16 connected to the bottom portion of the toilet bowl portion 14. The water drain passage portion 16 serves as a passage for waste that is discharged from the inside of the toilet bowl portion 14 to a sewage side water channel (not shown). The water drain passage portion 16 is provided with a trap portion 20 where sealing water 18 for blocking an airflow in the water flow direction is stored. To a downstream end portion of the trap portion 20, a connecting pipe (not shown) coming out from the floor 100 is connected, and the trap portion 20 is connected to the sewage side water channel via the connecting pipe.

FIG. 3 is a cross-sectional view taken along a line B-B of FIG. 2. As shown in FIG. 2 and FIG. 3, the toilet bowl portion 14 is provided with a bowl-like receiving surface portion 22 for receiving waste and a recessed portion 24 recessed downward from the lower edge portion of the receiving surface portion 22 and formed at the bottom portion of the toilet bowl portion 14. The receiving surface portion formed in an ellipse shape such that the longitudinal dimension becomes larger than the lateral dimension in a planar view. At a bottom surface portion of the recessed portion 24, an inlet 16 a of the water drain passage portion 16 is open.

FIG. 4 is a cross-sectional view taken along line C-C of FIG. 3. As shown in FIGS. 1, 2, and 4, the toilet main body 12 is provided with a rim portion 26, which forms a peripheral portion of an upper end opening 14 a of the toilet bowl portion 14. The rim portion 26 is provided with an inner circumferential wall portion 28, which forms an upper end portion of the inner circumferential wall portion of the toilet bowl portion 14 and is connected to an upper edge portion of the receiving surface portion 22, and an upper wall portion 30, which extends from the upper end opening 14 a to both the left and right sides and both the front and back sides of the flush toilet 10. Further, the rim portion 26 is provided with an outer circumferential wall portion 32, which extends downward from an outer circumferential end portion of the upper wall portion 30 on both the left and right sides and on the front side and forms an upper end portion of the outer circumference of the toilet main body 12.

Referring back to FIG. 3, the toilet main body 12 is provided with two rim water discharge ports 34L and 34R, which are formed on the inner circumferential wall portion 28 of the rim portion 26, and rim water passages 36L and 36R for supplying washing water to the two rim water discharge ports 34L and 34R. The toilet main body 12 is further provided with a common water passage 38 for supplying washing water to each of the two rim water passages 36L and 36R, and two rim water leading passages 40A and 40B, which are formed on the inner circumferential side of the inner circumferential wall portion 28 of the rim portion 26. The flush toilet 10 has one of main features in the rim water passage 36L. An explanation will be given first regarding the overview of a surrounding structure including the rim water passage 36L.

The two rim water discharge ports 34L and 34R include a left rim water discharge port 34L (first rim water discharge port) arranged on the left side of the flush toilet 10 and a right rim water discharge port 34R (second rim water discharge port) arranged on the right side of the flush toilet 10. From each rim water discharge port 34L, washing water is discharged to one side (in the counterclockwise direction in FIG. 3, and hereinafter simply referred to as counterclockwise direction) in the circumferential direction of the toilet bowl portion 14 along the inner circumferential surface of the inner circumferential wall portion 28 of the rim portion 26.

The right rim water discharge port 34R is arranged at the same level position as that of the left rim water discharge port 34L. The “level position” used here means a position in the vertical direction with reference to the floor. In the present embodiment, the entire left rim water discharge port 34L and the entire right rim water discharge port 34R are arranged at the same level position. However, only a portion of the rim water discharge port 34L and a portion of the rim water discharge port 34R need to be arranged at the same level position. Also, each of the rim water discharge ports 34L and 34R is arranged at a position shifted by an angle that is equal to 180 degrees around the center Cp (also see FIG. 1) of the upper end opening 14 a of the toilet bowl portion 14 in a planar view. The expression “equal” used here means that subjects to be compared with each other are the same or almost the same.

The two rim water passages 36L and 36R include a left rim water passage 36L (first rim water passage) for supplying washing water to the left rim water discharge port 34L and a right rim water passage 36R (second rim water passage) for supplying washing water to the right rim water discharge port 34R. Each of the rim water passages 36L and 36R is formed on the outer circumferential side of the toilet bowl portion 14. More specifically, each of the rim water passages 36L and 36R is formed on the outer circumferential side of a wall portion that forms the inner circumferential surface of the toilet bowl portion 14. The “wall portion that forms the inner circumferential surface of the toilet bowl portion 14” used here includes the receiving surface portion 22 and the inner circumferential wall portion 28 of the rim portion 26 of the toilet bowl portion 14.

Of both left and right portions 14L and 14R of the toilet bowl portion 14, the left rim water passage 36L is formed on the outer circumferential side and the left side of the inner circumferential wall portion of the left portion 14L. Also, the left rim water passage 36L is arranged so as not to pass through a lateral center line CL of the flush toilet 10 on the front side of the toilet bowl portion 14. Of the both left and right portions 14L and 14R of the toilet bowl portion 14, the right rim water passage 36R is formed on the outer circumferential side and the right side of the inner circumferential wall portion of the right portion 14R. The left portion 14L of the toilet bowl portion 14 means a portion arranged on the left side, which is one of the lateral sides, with respect to the lateral center line CL of the flush toilet 10. The right portion 14R of the toilet bowl portion 14 means a portion arranged on the right side with respect to the lateral center line CL of the flush toilet 10. The lateral center line CL means a straight line that extends along the longitudinal direction bisecting a lateral dimension Lx (see FIG. 1), which is the maximum lateral dimension of the outer surface portion of the flush toilet 10.

The rim water passages 36L and 36R are formed being branched to the left and right from a downstream end portion of the common water passage 38. A branching position 36 a of the rim water passages 36L and 36R is arranged behind the inner circumferential wall portion 28 of the rim portion 26. To the common water passage 38, washing water is supplied from a washing water supply device (not shown), and the washing water is guided to the inside of the rim water passages 36L and 36R in a direction Pa through the common water passage 38 (see also FIG. 2). The washing water supply device is formed of, for example, combination of a tank, a pump, and a water pipe.

The right rim water passage 36R is formed so as to extend the counterclockwise direction from the branching position 36 a, which serves as an upstream end portion, and the right rim water discharge port 34R is formed at a downstream end portion, which is located at an end position in the extending direction. The left rim water passage 36L will be described later in detail.

The two rim water leading passages 40A and 40B include a first rim water leading passage 40A formed so as to extend in the counterclockwise direction from the left rim water discharge port 34L and a second rim water leading passage 40B formed so as to extend in the counterclockwise direction from the right rim water discharge port 34R. The rim water leading passages 40A and 40B are for allowing washing water to reach the respective end positions from the respective start positions of the rim water leading passages 40A and 40B by guiding washing water discharged from the rim water discharge ports 34L and 34R so as to swirl.

As shown in FIG. 4, the second rim water leading passage 40B is provided with a shelf portion 40 a extending toward the outside of the toilet bowl portion 14 from an upper edge portion of the receiving surface portion 22 and an overhanging portion 40 b arranged above the shelf portion 40 a. The shelf portion 40 a is formed such that the slope of an upper surface portion thereof continuing to the upper edge of the receiving surface portion 22 is more gentle than the slope of an inner surface portion of the receiving surface portion 22. The overhanging portion 40 b is formed such that a lower surface portion thereof, which faces an upper surface portion of the shelf portion 40 a in the vertical direction, extends toward the inner side of the toilet bowl portion 14 in the radial direction. Although the first rim water leading passage 40A is not shown, the same applies to the first rim water leading passage 40A.

FIG. 3 is referred back. Having passing through the rim water leading passages 40A and 40B, washing water discharged from the rim water discharge ports 34L and 34R forms a swirling flow swirling inside the toilet bowl portion 14. This swirling flow serves as a water flow for washing the inner surface of the toilet bowl portion 14, particularly, the inner circumferential surface of the inner circumferential wall portion 28 of the rim portion 26 and the inner surface of the receiving surface portion 22.

Now an explanation for the left rim water passage 36L will be given. FIG. 5 is a cross-sectional view showing, in an enlarged view, the left rim water passage 36L, and FIG. 6 is a schematic diagram of a cross section cut along a line D-D of FIG. 5, the cross section being expanded in a plane. In FIG. 6, the flowing direction of washing water inside the left rim water passage 36 is shown by an arrow Pb (the same applies in FIG. 2).

As shown in FIG. 5, the left rim water passage 36L is arranged in a partial range Sa from the branching position 36 a, which serves as the upstream end portion thereof, to the other side (in the clockwise direction in FIG. 5, and hereinafter simply referred to as clockwise direction) in the circumferential direction of the toilet bowl portion 14 on the outer circumferential side of the left portion 14L of the toilet bowl portion 14. This range Sa means a range around a vertical axis that passes through the center Cp (also see FIG. 1) of the upper end opening 14 a of the toilet bowl portion 14. The left rim water passage 36L, as a whole, has a shape extending in the clockwise direction toward the front side from the back side of the flush toilet 10 on the outer circumferential side and left side of the toilet bowl portion 14.

As shown in FIGS. 5 and 6, the left rim water passage 36L is provided with a turned-back portion 42 leading washing water to turn back from the clockwise direction (the left direction in FIG. 6) to the counterclockwise direction (the right direction in FIG. 6), an outbound portion 44 continuing the upstream side of the turned-back portion 42, and an inbound portion 46 continuing to the downstream side of the turned-back portion 42.

The outbound portion 44 is formed so as to extend in the clockwise direction from the branching position 36 a of each of the rim water passages 36L and 36R, which serves as the upstream end portion thereof. The outbound portion 44 has an upstream portion 44 a provided on the upstream side, a downstream portion 44 b provided on the downstream side, and an intermediate portion 44 c connecting the upstream portion 44 a and the downstream portion 44 b.

The upstream portion 44 a is arranged at a position that is apart from the inbound portion 46 in the counterclockwise direction (the right direction in FIG. 6). The downstream portion 44 b is arranged below the inbound portion 46. The lower surface of the upstream portion 44 a is arranged at a position higher than the lower surface and the upper surface of the downstream portion 44 b. The upstream portion 44 a is thus arranged at a position higher than the downstream portion 44 b. The respective lower surfaces of the upstream portion 44 a and the downstream portion 44 b are formed to be parallel to a horizontal plane. The expression “to be parallel to” used here means that subjects to be compared with each other are completely parallel to each other or almost parallel to each other.

The lower surface of the intermediate portion 44 c is formed so as to smoothly connect the lower surface of the upstream portion 44 a and the lower surface of the downstream portion 44 b while being inclined with respect to the horizontal plane. Washing water flowing through the upstream portion 44 a flows the downstream portion 44 b after being led to the downward side when passing through the intermediate portion 44 c. As described, the intermediate portion 44 c has a function of leading washing water from the upstream portion 44 a to the downstream portion 44 b.

The turned-back portion 42 connects a downstream end portion of the outbound portion 44 and an upstream end portion of the inbound portion 46. The turned-back portion 42 has a shape where a downstream side portion 42 b of the turned-back portion 42 is located on one of the vertical sides (upper side) with respect to an upstream side portion 42 a of the turned-back portion 42.

The inbound portion 46 is arranged above a portion of the downstream portion 44 b of the outbound portion 44. The portion of the downstream portion 44 b of the outbound portion 44 and the inbound portion 46 are thus arranged while being lined up vertically. It can also be said that the portion of the downstream portion 44 b of the outbound portion 44, and the inbound portion 46 are arranged so as to overlap with each other vertically.

The inbound portion 46 is formed so as to extend in the counterclockwise direction from a position, which is an upstream end portion thereof, where the inbound portion 46 is connected to the turned-back portion 42, and the left rim water discharge port 34L provided so as to continue to a downstream end portion, which is located at an end position in the extending direction of the inbound portion 46. A portion of the first rim water leading passage 40A continuing to the left rim water discharge port 34L is also arranged while being lined up vertical with the portion of the downstream portion 44 b of the outbound portion 44.

FIG. 4 described previous is also a cross-sectional view taken along a line E-E of FIG. 6. As shown in FIGS. 4-6, on the inner side of the rim portion 26, a hollow portion 48 extending along the circumferential direction of the toilet bowl portion 14 is formed in the range Sa where the previously-described left rim water passage 36L is arranged. Inside the hollow portion 48, a partition wall portion 54 dividing an internal space 48 a of the hollow portion 48 in the vertical direction arranged in a range Sb where the downstream portion 44 b of the outbound portion 44 is arranged. The partition wall portion 54 is formed so as to extend along the circumferential direction of the toilet bowl portion 14. The turned-back portion 42 of the left rim water passage 36L, the outbound portion 44, and the inbound portion 46 are formed due to the partition wall portion 54 being arranged inside the internal space 48 a of the hollow portion 48. The portion of the downstream portion 44 b of the outbound portion 44, and the inbound portion 46 are thus formed due to the internal space 48 a of the hollow portion 48 being divided it the vertical direction by the partition wall portion 54.

As shown in FIG. 6, when washing water is introduced to the inside of the left rim water passage 36L from the common water passage 38, the washing water flows toward the clockwise direction (the left direction in FIG. 6) inside the outbound portion 44. When washing water is introduced to the inside of the turned-back portion 42 from the inside of the outbound portion 44, the washing water flows so as to turn back such that the flowing direction changes from the clockwise direction to the counterclockwise direction right direction in FIG. 6) at the turned-back portion 42. When washing water is introduced to the inside of the inbound portion 46 from the turned-back portion 42, the washing water flows toward the counterclockwise direct on inside the inbound portion 46, and the washing water is discharged from the left rim water discharge port 34L to the rear side of the flush toilet 10 and in the counterclockwise direction.

An explanation will now be given regarding operational effects of the above flush toilet 10. FIG. 7 is a cross-sectional view of a flush toilet according to a reference example, the flush toilet being viewed from the same viewpoint as that of FIG. 4. In FIG. 7, the portion of the outbound portion 44 and the inbound portion 46 are lined up in the lateral direction, and the internal space 48 a of the hollow portion 48 of the rim portion 26 is divided in lateral direction by the partition wall portion 54. In any of the examples in FIGS. 4 and 7, the outer width dimension La of the rim portion 26 and the cross-sectional shape of the hollow portion 48 are the same.

The magnitude of the discharge amount of washing water from the left rim water discharge port 34L is proportional to the passage cross-sectional area of a part having the smallest passage cross-sectional area in a water passage route from the upstream end portion of the left rim water passage 36L to the left rim water discharge port 34L. At a section where the outbound portion 44 and the inbound portion 46 are lined up, the passage cross-sectional area is likely to become the smallest in the water passage route of the left rim water passage 36L. Therefore, in order to have a structure suitable for increasing the discharge amount of washing water from the left rim water discharge port 34L, the passage cross-sectional area at the section where the outbound portion 44 and the inbound portion 46 are lined up is preferably able to be made to be large. In order to reduce the side of the outer width dimension La of the rim portion 26 while satisfying this requirement, the passage cross-sectional area at the section where the outbound portion 44 and the inbound portion 46 are lined up is thus made to be large in the vertical direction.

As shown in FIG. 7, when the outbound portion 44 and the inbound portion 46 are arranged while being lined up in the lateral direction, the dimension (vertical dimension) of the partition wall portion 54 separating the outbound portion 44 from the inbound portion also becomes larger as the passage cross-sectional area at the section where the outbound portion 44 and the inbound portion 46 are lined up becomes larger in the vertical direction. In contrast, as shown in FIG. 4, when the outbound portion 44 and the inbound portion 46 are arranged while being lined up in the vertical direction, the dimension of the partition wall portion 54 separating the outbound portion 44 from the inbound portion 46 does not become larger even when the passage cross-sectional area at the section where the outbound portion 44 and the inbound portion 46 are lined up becomes larger in the vertical direction. Therefore, when the outbound portion 44 and the inbound portion 46 are arranged while being lined up in the vertical direction, the passage cross-sectional area at the section where the outbound portion 44 and the inbound portion 46 are lined up can be made effectively large in the vertical direction while preventing an increase in the dimension of the partition wall portion 54 compared to a case where the outbound portion 44 and the inbound portion 46 are arranged while being lined up in the lateral direction. Therefore, a structure can be provided that is suitable for increasing the discharge amount of washing water from the left rim water discharge port 34L while reducing the outer width dimension La of the rim portion 26.

Also, since the width dimension Lb of the partition wall portion 54 is smaller in the example in FIG. 4 compared to the example in FIG. 7, a contact area with washing water passing through the inside of the downstream portion 44 b of the outbound portion 44 or washing water passing through the inside of the inbound portion 46 also becomes small. When this contact area of washing water and the partition wall portion 54 becomes small, water pressure that is applied to the partition wall portion 54 by the washing water also becomes small correspondingly. As a result of this, the thickness dimension Lc of the partition wall portion 54 required for securing strength can be made small, and, by enlarging the downstream portion 44 b of the outbound portion 44 or the internal space of the inbound portion 46 correspondingly, a structure can be achieved that is suitable for increasing the discharge amount of washing water from the left rim water discharge port 34L.

Since the inbound portion 46 is arranged above the portion of the downstream portion 44 b, which is a portion of the outbound portion 44, a vertical dimension Ld (see FIGS. 2, 4, and 6) from the upper end opening 14 a of the toilet bowl portion 14 to the left rim water discharge port 34L can be made smaller compared to a case where the inbound portion 46 is arranged below the portion of the downstream portion 44 b of the outbound portion 44. This vertical dimension Ld is also the vertical dimension of the overhanging portion 40 b. Intrinsically, it is difficult for washing water to reach a region between the upper end opening 14 a of the toilet bowl portion 14 and the rim water discharge ports 34L and 34R on the inner circumferential surface of the rim portion 26. Thus, insufficient washing is likely to occur. Therefore, if the inbound portion 46 is arranged below the outbound portion 44, the vertical dimension Ld of this region becomes large, and a range where insufficient washing is likely to occur getting large in the same way as in a so-called box rim. Regarding this point, according to the present embodiment, since the vertical dimension Ld of this region can be decreased, a range where insufficient washing is likely to occur can be decreased, and the inside of the toilet bowl portion 14 can be easily kept clean.

As shown in FIG. 3, the left rim water discharge port 34L discharges washing water to the rear side of the flush toilet 10, and the left rim water passage 36L, which supplies washing water to the left rim water discharge port 34L, is arranged so as not to pass through the lateral center line CL of the flush toilet 10 on the front side of the toilet bowl portion 14. Therefore, in discharging washing water in the same direction, the distance of the water passage route of washing water inside the left rim water passage 36L can be reduced compared to a layout of the left rim water passage 36L where the left rim water passage 36L passes through the lateral center line CL on the front side of the toilet bowl portion 14. Therefore, there are also advantages where washing water having strong force can be more easily discharged from the left rim water discharge port 34L and where more favorable toilet bowl washing capability can be more easily obtained.

Further, the toilet main body 12 having the left rim water passage 36L stated above can be obtained by cast molding. More specifically, as shown in FIGS. 4-6, the toilet main body 12 is formed of the partition wall portion 54 described previous an upper surface side portion 56 including an upper surface portion of the toilet main body 12, and a toilet bowl side portion 58 located below the upper surface side portion 56. A boundary position of the upper surface side portion 56 and the toilet bowl side portion 58 is set at a position where the hollow portion 48 is divided in the vertical direction. The portions 54, 56, and 58 are separately formed by cast molding, and, by connecting these portions by adhesion or the like, the toilet main body 12 is formed.

Further, as shown in FIG. 1, the left rim water passage 36L is arranged so as to pass through the inside of the rim portion 26 on the left side (one side in the lateral direction) of the upper end opening 14 a of the toilet bowl portion 14 in a planar view. Further, in the planar view, the left rim water passage 36L is arranged so as to pass through the inside of the rim portion 26 at a section where the lateral dimension of the rim portion 26 from an outer surface portion on the left side of the rim portion 26 to the upper end opening 14 a becomes one fourth or less of the lateral dimension Lx of the flush toilet 10. In the present embodiment, a section located on the front side (the upper side in the figure) of a section where an alternate long and short dash line Le crosses is a section where the lateral dimension of the rim portion 26 becomes one forth or less. Further, in the planar view, the left rim water passage 36L according to the present embodiment is arranged so as to pass through the inside of the rim portion 26 at a section where the lateral dimension of the rim portion 26 from the outer surface portion on the left side of the rim portion 26 to the upper end opening 14 a becomes one sixth of the lateral dimension Lx of the flush toilet 10. In the present embodiment, a section located on the front side (the upper side in the figure) of a section where an alternate long and short dash line Lf crosses is a section where the lateral dimension of the rim portion 26 becomes one sixth or less.

FIG. 8 is a lateral cross-sectional view showing a flush toilet 10 according to a second embodiment, and FIG. 9 is a schematic diagram of the flush toilet 10 according to the second embodiment, the flush toilet 10 being viewed from the same viewpoint as that of FIG. 6. A toilet main body 2 is provided with a water draining passage 60 for discharging water inside the left rim water passage 36L. In FIGS. 6 and 9, the flowing direction of water inside the water draining passage 60 is shown by an arrow Pc.

The water draining passage 60 allows the left rim water passage 36L and the internal space of the trap portion 20 to communicate with each other. The water draining passage 60 has a water introducing inlet 60 a for introducing water from the inside of the left rim water passage 36L to the inside of the water draining passage 60 and a drainage outlet 60 b for discharging water from the inside of the water draining passage 60 to the inside of the trap portion 20. The water introducing inlet 60 a is open at the lower surface of the downstream portion 44 b of the left rim water passage 36L. The upper surface of the left rim water passage 36L is formed so as to be located above the water introducing inlet 60 a in a range Sa (see FIG. 5), which is from the upstream end portion of the left rim water passage 36L to the left rim water discharge port 34L.

Thereby, water within the previously-described range Sa including the downstream portion 44 b of the left rim water passage 36L is discharged to the inside of the trap portion 20 via the water draining passage 60 after the supplying of washing water from a washing water supply device is completed. This allows a space where gas can circulate to be formed in the range from the upstream end portion of the left rim water passage 36L to the left rim water discharge port 34L during a non-washing period. The expression “non-washing period” used here means a period during a standby mode before the starting washing caused by the supplying of washing water to the inside of the toilet bowl portion 14 from the washing water supply device.

Due to the above structure, an intermediate portion in the range from the upstream end portion of the left rim water passage 36L to the left rim water discharge port 34L can be prevented from being submerged completely due to remaining water after the supplying of washing water from the washing water supply device is completed. Therefore, in the case of using the flush toilet 10 in a cold district or the like, a situation can be prevented where washing water cannot be supplied to the left rim water discharge port 34L through the left rim water passage 36L due to the freezing of remaining water inside the left rim water passage 36L, and measures against freezing can be taken.

In addition to this, remaining water inside the rim water passages 36L and 36R can be discharged to the water drain passage portion 16 through the water draining passage 60 without allowing the remaining water pass through the inside of the toilet bowl portion 14 after the supplying of washing water from the washing water supply device is completed. Therefore, remaining water inside the rim water passages 36L and 36R can be prevented from flowing down from the rim water discharge ports 34L and 34R over a long period of time in the form of streaks of water (hereinafter, referred to as water streaks), and a decrease in the appearance due to water streaks can be prevented.

In the case of a layout where the inbound portion 46 of the left rim water passage 36L is arranged above the downstream portion 44 b of the outbound portion 44, water inside the downstream portion 44 b of the outbound portion 44 cannot be discharged from the left rim water discharge port 34L. Even in the case of such a layout, there is a great advantage from the perspective of being able to take measures against freezing by discharging water in a range including the inside of the downstream portion 44 b of the outbound portion 44.

Also, in the example in FIG. 9, an explanation has been given regarding an example where the water draining passage 60 for discharging water inside the left rim water passage 36L is formed separately from the rim water passages 36L and 36R. In addition to this, the water draining passage 60 may be formed by the right rim water passage 36R. The upper surface of the outbound portion 44 of the left rim water passage 36L and the upper surface of the right rim water passage 36R are formed so as to be located above the lower surface of the outbound portion 44 of the left rim water passage 36L and the lower surface of the right rim water passage 36R, respectively. Thereby, during a non-washing period, washing water inside the range including the downstream portion 44 b of the left rim water passage 36L is discharged from the right rim water discharge port 34R via the right rim water passage 36R. As a result, a space is formed where gas can circulate in the range from the upstream end portion of the left rim water passage 36L to the left rim water discharge port 34L.

At this time, the lower surface of the outbound portion 44 at the upstream portion 44 a and the lower surface of the outbound portion 44 at the downstream portion 44 b maybe continuous with no difference in level without providing any inclination to the intermediate portion 44 b of the outbound portion 44 of the left rim water passage 36L (see FIG. 6). Further, the right rim water discharge port 34R may be arranged at a level position that is lower than that of the left rim water discharge port 34L at this time. This means that the right rim water discharge port 34R is arranged at the same level position as that of the downstream portion 44 b of the outbound portion 44 of the left rim water passage 36L.

While the present invention has been described based on the embodiments, the embodiments are merely illustrative of the principles and applications of the present invention. Additionally, many variations and changes in arrangement may be made in the embodiments without departing from the sprit of the present invention as defined by the appended claims.

For the flush toilet 10, the inside of the toilet bowl portion 14 may be washed by a washing technique of a wash down type, a siphon type, and the like. For the flush toilet 10, a water supply technique of a water supply direct pressure type, a gravity water supply type where the gravity is used, or the like may be used. The toilet main body 12 has been explained using a floor mounted type toilet as an example. Alternatively, the toilet main body 12 may be a wall mounted type toilet that is mounted while being hung on a side wall surface in a toilet room. Also, other than ceramics, a resin, etc., may be used as a material of the toilet main body 12.

The flush toilet 10 may be provided with the left and right rim water passages 36L and 36R as in the example FIG. 3 or may be provided with only one rim water passage. An example has been explained where one rim water discharge port is formed for one rim water passage. Alternatively, two or more rim water discharge ports may be formed for one rim water passage. Also, an example has been explained where the rim water discharge ports 34L and 34R discharge washing water toward one side in the circumferential direction along the inner circumferential surface of the rim portion 26. The rim water discharge ports 34L and 34R only need to discharge washing water to the inside of the toilet bowl portion 14, and, besides this direction, the rim water discharge ports 34L and 34R may discharge washing water in the downward direction.

An example has been explained where, in the rim water passage 36L, the inbound portion 46 is arranged above a portion of the downstream portion 44 b of the outbound portion 44. Alternatively the inbound portion 46 may be arranged below a portion of the outbound portion 44. An example has been explained where, in the left rim water passage 36L, the entire inbound portion 46 is arranged while being lined up in the vertical direction with a portion of the outbound portion 44. At least a portion of the inbound portion 46 needs to be arranged while being lined up in the vertical direction.

An example has been explained where only the lower surface of the intermediate portion 44 c of the outbound portion 44 is formed so as to smoothly connect the lower surface of the upstream portion 44 a and the lower surface of the downstream portion 44 b while being inclined with respect to the horizontal plane. In addition to this, the upper surface of the intermediate portion 44 c may also be formed so as to smoothly connect the upper surface of the upstream portion 44 a and the upper surface of the downstream portion 44 b while being inclined with respect to the horizontal plane.

The drainage outlet 60 b of the water draining passage 60 may be used as a jet discharge port that forms a water flow for promoting the discharging of waste discharging washing water to the recessed portion 24 of the toilet bowl portion 14 and the sealing water 18 inside the water drain passage portion 16 at the time of toilet washing. In this case, for example, the drainage outlet 60 b is formed at position where washing water can be discharged toward the downstream side of the water drain passage portion 16.

The following technical ideas are derived by generalizing the invention embodied according to the above embodiments and exemplary variations.

In the flush toilet according to the embodiment described in the previously-described means to solve the problem, the inbound portion may be arranged above a portion of the outbound portion. According to this embodiment, on the inner circumferential surface of the rim portion, the vertical dimension from the upper end opening of the toilet bowl portion to the rim water discharge port can be made smaller compared to a case where the inbound portion is arranged below the portion of the outbound portion. Therefore, range where insufficient washing is likely to occur can be decreased, and the inside of the toilet bowl portion can be easily kept clean.

The flush toilet according to the previously-described embodiment may be provided with a water draining passage for discharging water inside the portion of the outbound portion. According to this embodiment, the portion of the outbound portion arranged below the inbound portion can be prevented from being submerged completely due to remaining water. Therefore, in the case of using the flush toilet in a cold district or the like, a situation can be prevented where washing water cannot be supplied to the rim water discharge port through the rim water passage due to the freezing of remaining water inside the rim water passage, and measures against freezing can be taken.

In the flush toilet according to the previously-described embodiment, the first rim water passage may be arranged so as to pass through one side in the lateral direction with respect to the upper end opening in a planar view.

The flush toilet according to the previously-described embodiment may be provided with a second rim water discharge port formed or the inner circumferential wall portion of the rim portion and arranged at the same level position as that of the first rim water discharge port or at a level position that is lower than that of the first rim water discharge port. 

1. A flush toilet comprising: a toilet bowl portion; a rim portion that forms a peripheral portion of an upper end opening of the toilet bowl portion; a first rim water discharge port that is formed on an inner circumferential wall portion of the rim portion; and a first rim water passage that is formed on the outer circumferential side of the toilet bowl portion and is for supplying washing water to the first rim water discharge port, wherein the first rim water passage has a turned-back portion that guides washing water to turn back from one side to the other side in the circumferential direction of the toilet bowl portion, a portion of an outbound portion and a portion of an inbound portion that continue to the turned-back portion being arranged while being lined up in the vertical direction.
 2. The flush toilet of claim 1, wherein the inbound portion is arranged above the portion of the outbound portion.
 3. The flush toilet of claim 2, comprising a water draining passage for discharging water inside the portion of the outbound portion.
 4. The flush toilet of claim 1, wherein the first rim water passage is arranged so as to pass through one side in the lateral direction with respect to the upper end opening in a planar view.
 5. The flush toilet of claim 1, comprising a second rim water discharge port that is formed on the inner circumferential wall portion of the rim portion, wherein the second rim water discharge port is arranged at the same level position as that of the first rim water discharge port.
 6. The flush toilet of claim 2, wherein the first rim water passage is arranged so as to pass through one side in the lateral direction with respect to the upper end opening in a planar view.
 7. The flush toilet of claim 3, wherein the first rim water passage is arranged so as to pass through one side in the lateral direction with respect to the upper end opening in a planar view.
 8. The flush toilet of claim 2, comprising a second rim water discharge port that is formed on the inner circumferential wall portion of the rim portion, wherein the second rim water discharge port is arranged at the same level position as that of the first rim water discharge port.
 9. The flush toilet of claim 3, comprising a second rim water discharge port that is formed on the inner circumferential wall portion of the rim portion, wherein the second rim water discharge port is arranged at the same level position as that of the first rim water discharge port.
 10. The flush toilet of claim 4, comprising a second rim water discharge port that is formed on the inner circumferential wall portion of the rim portion, wherein the second rim water discharge port is arranged at the same level position as that of the first rim water discharge port. 